Shimano Di2 EW90 Junction-A Box (3 Port)Shimano Di2 EW90 Junction A Box (3 Port) Say goodbye to poor shifting control, thanks to the Junction A Box from Shimano. Mounting seamlessly to your bike stem, it connects with E Tube wires from D12 shifters and a downtube junction wire. This junction A is required to connect the shifters via E tube wires to the downtube junction wire 3 port design, one for downtube wire to bottom bracket junction, two for shifter connection Battery level indicator